Radio frequency identification (RFID) of items through the use of RFID tags has been known for more than 50 years. It was first described in the Proceedings of the IRE, October 1948, in an article, Communication by Means of Reflected Power, Harry Stockman, pp. 1196–1204. RFID tags may be active or passive. The passive tags are minute, in the order of 0.4 mm, and cost a few cents each. These passive RFID tags do not have their own power supply and have a signal range in the order of 5 feet or less. On the other hand, active RFID tags usually have their own power source and currently may have ranges in the order of hundreds of feet and are more expensive. Also, the active RFID tags are commonly referred to as RFID transponders. Usage of RFID tags/transponders has been extensively documented for a wide variety of tracking functions. Low frequency RFID tags are commonly used for animal identification or anti-theft systems in automobiles, for example. Higher frequency RFID tags are used for book tracking, pallet tracking or airline baggage tracking. There are, of course, well developed technologies in the higher frequency RFID tag tracking systems, such as UHF RFID and Microwave RFID tags.
Unlike active RFID tags that require a small power source of some kind, passive tags do not require power. They get their operating power from the energy generated by the tag reader or transceiver. Also, passive tags have an almost unlimited operating life.
The RFID product identification is an old and well developed technology. Some US patents that are representative of the art are: U.S. Pat. Nos. 4,918,416; 4,580,041; 4,236,068; 3,970,824; and 6,742,714. With the rapidly expanding usage of RFID tag systems in both the business and consumer sectors, the prices of the systems and tags have been dropping. This, in turn, has resulted in the industry seeking new uses of this technology. The present invention provides such a new function directed to a particular consumer market, i.e. householders responsible for the routine operation of a household.